Digital documents can be ameliorated through document processing that enhances the color, contrast and other attributes of the document. Different processing methods are used to enhance different content types. In some cases, processing that enhances one content type will degrade another content type. For example, a process that enhances the legibility of text may degrade attributes of a continuous-tone (contone) image, such as a digital photograph. In mixed-content documents, different content types must be segmented in order to provide optimum document processing. Content types include contone images, halftone images, text and others. Some document types can be further delineated for more optimal processing. For example, contone regions can be separated into pictorial and non-pictorial regions.
The identification and delineation of document areas by content type is an essential part of segmentation for document processing. Once each document region is segmented, each region can be processed separately according to the specific needs of the content type.